1. Fiend of the Invention
The invention concerns a cosmetic product for rapidly delivering a sunless tanning or a glow effect upon skin.
2. The Related Art
Sunless tanning agents are formulated into two types of cosmetic products. Of these, the most traditional is the self-tanning lotion. The imparted benefit is to achieve a skin coloration equivalent to that from basking in the sun. More recently, a second product category has arrived. Therein a sunless tanning agent in small amounts is added to a typical moisturizing lotion. A “glow or shine” is thereby imparted. Glow or shine is a major factor in the appearance of healthy looking skin.
Most prominent among the sunless tanning agents is dihydroxyacetone (“DHA” which is also chemically known as 1,3-dihydroxy-2-propanone). DHA is believed to exert its effect through interactions between its hydroxyl groups and the amino groups of amino acids and peptides naturally occurring in the hydrolipid pellicle and first layers of the stratum corneum of the skin. These so-called Maillard reactions are believed (see, e.g., Bobin et al., J. Soc. Cosmet. Chem. 35: 255 (1984)) to lead to formation of brown pigments in the skin, thereby giving it an appearance similar to that of a naturally obtained tan.
WO 2007/017921 A1 (Shiseido Company, Ltd.) reports on a self-tanning cosmetic with dihydroxyacetone and inorganic pigment powder. The powder is prepared by subjecting an inorganic pigment to a surface coating of silica followed by a hydrophobic treatment. The finished cosmetic is said to be free of any color change and of the evolution of an offensive odor, has high storage stability and can establish both the desired performance immediately and after application to the skin owing to the pigment and a long lasting tanning effect owing to dihydroxyacetone.
Although there has been great progress in delivering effects of self-tanning, considerable further progress is needed. In particular, it would be desirable to achieve almost instantaneous glow, shine or tanning upon application to bridge the relatively long induction period of a sunless tanning agent. Further, it would be aesthetically and psychologically desirable to retain a distinction between the color of the delivering cosmetic formula and that of the eventual tan.